<?php
namespace App\Service;

class PasswordHash
{
    private $itoa64;
    private $iteration_count_log2;
    private $portable_hashes;
    private $random_state;

    // 构造
    public function __construct($iteration_count_log2, $portable_hashes)
    {
        $this->itoa64 = './0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';

        if($iteration_count_log2 < 4 || $iteration_count_log2 > 31){
            $iteration_count_log2 = 8;
        }

        $this->iteration_count_log2 = $iteration_count_log2;
        $this->portable_hashes      = $portable_hashes;
        $this->random_state         = microtime();
        if(function_exists('getmypid')){
            $this->random_state .= getmypid();
        }
    }


    private function get_random_bytes($count)
    {
        $output = '';
        if(is_readable('/dev/urandom') &&
           ($fh = @fopen('/dev/urandom', 'rb'))){
            $output = fread($fh, $count);
            fclose($fh);
        }

        if(strlen($output) < $count){
            $output = '';
            for($i = 0; $i < $count; $i += 16){
                $this->random_state = md5(microtime().$this->random_state);
                // 输出
                $output .= pack('H*', md5($this->random_state));
            }
            $output = substr($output, 0, $count);
        }

        return $output;
    }

    private function encode64($input, $count)
    {
        $output = '';
        $i      = 0;
        do{
            $value  = ord($input[$i++]);
            $output .= $this->itoa64[$value & 0x3f];
            if($i < $count){
                $value |= ord($input[$i]) << 8;
            }
            $output .= $this->itoa64[($value >> 6) & 0x3f];
            if($i++ >= $count){
                break;
            }
            if($i < $count){
                $value |= ord($input[$i]) << 16;
            }
            $output .= $this->itoa64[($value >> 12) & 0x3f];
            if($i++ >= $count){
                break;
            }
            $output .= $this->itoa64[($value >> 18) & 0x3f];
        } while($i < $count);

        return $output;
    }

    private function gensalt_private($input)
    {
        $output = '$P$';
        $output .= $this->itoa64[min(
            $this->iteration_count_log2 +
            ((PHP_VERSION >= '5') ? 5 : 3),
            30
        )];
        $output .= $this->encode64($input, 6);

        return $output;
    }

    private function crypt_private($password, $setting)
    {
        $output = '*0';
        if(substr($setting, 0, 2) == $output){
            $output = '*1';
        }

        $id = substr($setting, 0, 3);
        # We use "$P$", phpBB3 uses "$H$" for the same thing
        if($id != '$P$' && $id != '$H$'){
            return $output;
        }

        $count_log2 = strpos($this->itoa64, $setting[3]);
        if($count_log2 < 7 || $count_log2 > 30){
            return $output;
        }

        $count = 1 << $count_log2;
        $salt  = substr($setting, 4, 8);
        if(strlen($salt) != 8){
            return $output;
        }

        # We're kind of forced to use MD5 here since it's the only
        # cryptographic primitive available in all versions of PHP
        # currently in use.  To implement our own low-level crypto
        # in PHP would result in much worse performance and
        # consequently in lower iteration counts and hashes that are
        # quicker to crack (by non-PHP code).
        if(PHP_VERSION >= '5'){
            $hash = md5($salt.$password, true);
            do{
                $hash = md5($hash.$password, true);
            } while(--$count);
        } else{
            $hash = pack('H*', md5($salt.$password));
            do{
                $hash = pack('H*', md5($hash.$password));
            } while(--$count);
        }

        $output = substr($setting, 0, 12);
        $output .= $this->encode64($hash, 16);

        return $output;
    }

    private function gensalt_extended($input)
    {
        $count_log2 = min($this->iteration_count_log2 + 8, 24);
        # This should be odd to not reveal weak DES keys, and the
        # maximum valid value is (2**24 - 1) which is odd anyway.
        $count = (1 << $count_log2) - 1;

        $output = '_';
        $output .= $this->itoa64[$count & 0x3f];
        $output .= $this->itoa64[($count >> 6) & 0x3f];
        $output .= $this->itoa64[($count >> 12) & 0x3f];
        $output .= $this->itoa64[($count >> 18) & 0x3f];

        $output .= $this->encode64($input, 3);

        return $output;
    }

    private function gensalt_blowfish($input)
    {
        # This one needs to use a different order of characters and a
        # different encoding scheme from the one in encode64() above.
        # We care because the last character in our encoded string will
        # only represent 2 bits.  While two known implementations of
        # bcrypt will happily accept and correct a salt string which
        # has the 4 unused bits set to non-zero, we do not want to take
        # chances and we also do not want to waste an additional byte
        # of entropy.
        $itoa64 = './ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';

        $output = '$2a$';
        $output .= chr(ord('0') + $this->iteration_count_log2 / 10);
        $output .= chr(ord('0') + $this->iteration_count_log2 % 10);
        $output .= '$';

        $i = 0;
        do{
            $c1     = ord($input[$i++]);
            $output .= $itoa64[$c1 >> 2];
            $c1     = ($c1 & 0x03) << 4;
            if($i >= 16){
                $output .= $itoa64[$c1];
                break;
            }

            $c2     = ord($input[$i++]);
            $c1     |= $c2 >> 4;
            $output .= $itoa64[$c1];
            $c1     = ($c2 & 0x0f) << 2;

            $c2     = ord($input[$i++]);
            $c1     |= $c2 >> 6;
            $output .= $itoa64[$c1];
            $output .= $itoa64[$c2 & 0x3f];
        } while(1);

        return $output;
    }

    // 执行加密
    public function HashPassword($password)
    {
        $random = '';

        if(CRYPT_BLOWFISH == 1 && !$this->portable_hashes){
            $random = $this->get_random_bytes(16);
            $hash   = crypt($password, $this->gensalt_blowfish($random));
            if(strlen($hash) == 60){
                return $hash;
            }
        }

        if(CRYPT_EXT_DES == 1 && !$this->portable_hashes){
            if(strlen($random) < 3){
                $random = $this->get_random_bytes(3);
            }
            $hash = crypt($password, $this->gensalt_extended($random));
            if(strlen($hash) == 20){
                return $hash;
            }
        }

        if(strlen($random) < 6){
            $random = $this->get_random_bytes(6);
        }
        $hash = $this->crypt_private($password, $this->gensalt_private($random));
        if(strlen($hash) == 34){
            return $hash;
        }

        # Returning '*' on error is safe here, but would _not_ be safe
        # in a crypt(3)-like function used _both_ for generating new
        # hashes and for validating passwords against existing hashes.
        return '*';
    }

    // 验证密码
    public function CheckPassword($password, $stored_hash)
    {
        $hash = $this->crypt_private($password, $stored_hash);
        if($hash[0] == '*'){
            $hash = $this->crypt_private($password, $stored_hash);
        }

        return $hash == $stored_hash;
    }
}

?>
